KR20200070403A - Method for manufacturing nickel-based alloy - Google Patents

Abstract

The present invention relates to a method for producing a nickel-based alloy, in which:-the electrode is produced by VIM, VOF or VLF; -For stress reduction and aging, the electrode is heat treated in the furnace for 10 to 336 hours in a temperature range of 500 to 1300 °C, and the heat treatment is a minimum of 10 hours and a maximum of 48 hours in a temperature range of 1000 to 1300 °C Is applied during; -The electrode is cooled to a temperature of room temperature or higher and less than 900°C in air or in a furnace; -The cooled electrode is then remelted by ESR at a remelting rate of 3.0 to 10 kg/min to obtain an ESR block; -The ESR block is cooled in air or in a furnace to a temperature above room temperature and below 900° C., the ESR block is at a remelting rate of 3.0 to 10 kg/min and less than 15%, more preferably 10 In the range of remelting rate fluctuations less than %, ideally less than 5%, remelted again by VAR; -The remelted VAR block is heat treated for 10 to 336 hours in a temperature range of 500 to 1250°C; -Then, the VAR block has a desired product shape and dimensions through hot forming or cold forming.

Description

Method for manufacturing nickel-based alloy

The present invention relates to a method for producing a nickel-based alloy.

EP 1 377 690 B1 discloses a method for the production of nickel-based superalloys, which is substantially free of positive and negative segregation, which includes:

-Casting an alloy in a casting mold,

Heating the alloy to at least 649° C. and annealing and over-aging for at least 10 hours.

Remelting the alloy electroslag at a melting rate of at least 3.63 kg/min,

-Moving the alloy into a heating oven within 4 hours after complete solidification,

-Maintaining the alloy in a heating oven for at least 10 hours at a first temperature between 316 °C and 982 °C,

-Raising the furnace temperature from the first temperature to a second temperature of at least 1163 °C, so as to prevent thermal stress in the alloy,

-Maintaining the alloy at a second temperature for at least 10 hours,

-Re-melting the vacuum arc of the alloy at a melting rate of 3.63 to 5 kg/min to produce a VAR ingot.

The nickel-based alloy preferably relates to alloy 718 or alloy 706.

As is commonly known, heat treatment in higher temperature ranges (eg, 500 to 1250° C.) can be used to homogenize segregation and relieve material stress.

The object of the present invention is to provide an alternative and cheaper method for the production of nickel-based alloys by means of which the microstructure can be improved as well as the reduction of defects introduced into the material during the last remelting step, in order to accommodate future customer needs. Is to provide a way. Compared to the method disclosed in EP 1 377 690 B1, the cost incurred by complex process control between the first and second remelting must be avoided. And quality must be improved significantly by avoiding defects caused by melting and remelting. This task is accomplished by the following method for producing nickel-based alloys:

-Electrodes are created by VIM, VOD or VLF,

-For stress reduction and overaging, the electrode is heat treated in the furnace for 10 to 336 hours in a temperature range of 500 to 1300 °C, where the heat treatment is applied in a temperature range of 1000 °C to 1300 °C for at least 10 to 48 hours And

-The electrode is cooled to a temperature of room temperature or higher and less than 900 °C in air or in a furnace,

-The cooled electrode is then remelted by ESR at a remelting rate of 3.0 to 10 kg/min to obtain an ESR ingot,

-ESR ingots are cooled in air or in furnaces to temperatures above room temperature and below 900 °C,

The ESR ingot is remelted again by VAR at a remelting rate of 3.0 to 10 kg/min, and at a range of remelting rate of less than 15%, more preferably less than 10%, ideally less than 5%,

-The remelted VAR ingot is heat treated for 10 to 336 hours in a temperature range of 500 to 1250 °C,

-Next, the VAR ingot will then have the desired product shape and dimensions through hot and/or cold working.

Advantageous further development of the method according to the invention (eg, an additional step of remelting by VAR) can be deduced from the dependent claims.

Compared to the prior art, the heat treatment step after remelting by ESR is eliminated, and the remelting rate is specified more accurately. Therefore, the heat treatment is performed only on the basic electrode, not the ESR ingot, as described in the prior art. The material produced in this way has a much lower content of defects caused by remelting.

Due to the selective heat treatment of the VIM ingot, the internal stress is relieved and segregation defects are eliminated. This has a positive effect on the subsequent remelting stages of ESR and VAR.

This task is also preferably achieved by the following method for producing nickel-based alloys:

-The electrode is created by VIM,

-When the nickel-based alloy forms a gamma prime phase: the electrode is introduced into the furnace, before it is colder than 200 °C, ideally before it is colder than 250 °C,

-For stress reduction and over-aging, the electrodes are heat treated in the furnace for 10 to 336 hours in a temperature range of 500 to 1250 °C in the furnace,

-The electrode is cooled to a temperature of room temperature or higher and less than 900 °C in air or in a furnace,

-The surface of the electrode is machined (e.g. by brushing, grinding, pickling, cutting, scalping, etc.) for defect removal and cleaning,

-The cooled electrode is then remelted by ESR at a remelting rate of 3.0 to 10 kg/min to obtain an ESR ingot with a diameter of 400 to 1500 mm,

-ESR ingots are cooled in air or in furnaces to temperatures above room temperature and below 900 °C,

-If necessary, the surface of the ESR ingot is machined for defect removal and cleaning (eg, by brushing, grinding, pickling, cutting, scalping, etc.).

-The cooled ESR ingot is further heat treated for 10 to 336 hours in a temperature range of 500 to 1250 °C,

-ESR ingots are cooled in air or in furnaces to temperatures below room temperature and below 870 °C,

The ESR ingot is remelted again by VAR at a remelting rate of 3.0 to 10 kg/min, and at a range of remelting rate of less than 15%, more preferably less than 10%, ideally less than 5%, VAR ingots having a diameter of 400 to 1500 mm are obtained,

-When the nickel-based alloy forms a gamma prime phase: the VAR ingot is introduced into the furnace before it is colder than 200 °C in the upper region, ideally before it is colder than 250 °C,

-The remelted VAR ingot is heat treated for 10 to 336 hours in a temperature range of 500 to 1250 °C,

-The VAR ingot is cooled in the air or in the furnace to a temperature above room temperature and below 900°C, or while it is hotter than 850°C, it is transferred to the hot working process,

-The VAR ingot will have the desired product shape (eg ingot, bar, wire, sheet, strip, foil) and dimensions by hot and/or cold working (eg forging, rolling, drawing).

It may be advantageous for the surface to be machined (eg by brushing, grinding, pickling, cutting, scalping, etc.) before the electrode is first remelted. In this process, defects can be eliminated, which may not be removed by further remelting and damage subsequent applications.

According to a further idea of the invention, the ESR ingot undergoes additional surface machining (e.g., by brushing, grinding, pickling, cutting, scalping, etc.) prior to VAR remelting, in this process, by additional remelting. It is also possible to eliminate defects that cannot be eliminated.

According to a further idea of the invention, remelting by VAR is performed directly instead of remelting by ESR.

This method can be applied to any Ni alloy and especially to the alloys according to Tables 1 and 11 to 13.

In the following, an alloy composition is provided which can be produced by process parameters according to the invention. All values are wt%:

Up to 0.25 wt% C;

S up to 0.03 wt%;

Cr of 17 to 32 wt%;

33 to 72 wt% Ni;

Up to 1 wt% Mn;

Up to 1 wt% Si;

0 to 10 wt% Mo;

Ti up to 3.25 wt%;

Up to 5.5 wt% Nb;

Up to 0.5 wt% Cu;

Up to 25 wt% Fe;

Up to 3.15 wt% Al;

Up to 0.6 wt% V;

Zr up to 0.12 wt%;

Up to 35 wt% Co; and

Manufacturing-related impurities.

Also, optionally:

Up to 5.2 wt% Nb+Ta;

Up to 0.02 wt% B;

SE up to 0.0005 wt%;

Up to 0.00005 wt% Bi;

Pb up to 0.002 wt%;

P. up to 0.03 wt%

Advantageously, the following atoms can be adjusted as follows:

Up to 0.2 wt% C;

S up to 0.02 wt%;

Cr of 17 to 25 wt%;

45 to 58 wt% Ni;

Up to 0.6 wt% Mn;

Up to 0.4 wt% Si;

0 to 6.1 wt% Mo;

0.1 to 2.7 wt% of Ti;

Up to 1.7 wt% Al;

Up to 13 wt% Co.

In the following, examples of alloys based on alloy 718 are presented:

Up to 0.08 wt% C;

S up to 0.015 wt%;

Cr of 17 to 21 wt%;

50 to 55 wt% Ni;

Mn up to 0.35 wt%;

Up to 0.35 wt% Si;

2.8 to 3.3 wt% Mo;

0.65 to 1.15 wt% of Ti;

4.75 to 5.5 wt% of Nb;

Up to 0.3 wt% Cu;

6 to 25 wt% Fe;

Up to 0.015 wt% P;

0.2 to 0.8 wt% Al;

Up to 1 wt% Co;

Up to 0.006 wt% B;

Ta of up to 0.05 wt%;

Pb up to 0.001 wt%;

Se up to 0.0005 wt%;

Bi. up to 0.00005 wt%

Alternatively, this alloy can also have a higher Ni content.

Up to 0.1 wt% C;

S up to 0.03 wt%;

Cr of 17 to 32 wt%;

58 to 79 wt% Ni;

Up to 0.6 wt% Nb;

Up to 18 wt% Fe;

Up to 0.1 wt% C;

S up to 0.02 wt%;

Cr of 17 to 30 wt%;

58 to 72 wt% Ni;

Up to 1 wt% Mn;

Up to 1 wt% Si;

0 to 10 wt% Mo;

Ti up to 3.25 wt%;

Up to 4.1 wt% Nb;

Up to 0.5 wt% Cu;

Up to 18 wt% Fe;

Up to 3.15 wt% Al;

Up to 0.6 wt% V;

Zr up to 0.1 wt%;

Up to 15 wt% Co.

Also, optionally:

Up to 0.008 wt% B;

Se up to 0.0005 wt%;

Up to 0.00005 wt% Bi;

Pb up to 0.002 wt%;

P. up to 0.03 wt%

The following additional limitations can be considered:

0.01 to 0.04 wt% C;

Up to 0.5 wt% Mn;

Up to 0.5 wt% Si;

Cu up to 0.2 wt%.

Also, optionally as needed:

8 to 10 wt% Mo.

In the following, examples of alloys based on alloy 780 are presented:

Up to 0.1 wt% C;

S up to 0.015 wt%;

Up to 0.03 wt% N;

Cr of 16 to 20 wt%;

26 to 62 wt% Ni;

Up to 0.5 wt% Mn;

Up to 0.3 wt% Si;

2 to 4 wt% Mo;

0.1 to 1 wt% Ti;

Up to 0.5 wt% Cu;

Up to 10 wt% Fe;

Up to 0.03 wt% P;

1 to 3 wt% Al;

Up to 0.01 wt% Mg;

Up to 0.01 wt% Ca;

Zr up to 0.05 wt%;

15 to 28 wt% Co;

Up to 0.02 wt% B;

Up to 0.02 wt% O;

4-6 wt% of Nb+Ta.

The material produced by this manufacturing process is significantly less defective (50%) with a comparative defect size of 0.8 mm, typically on ultrasound inspection.

The method according to the invention is preferably intended to be used for the following alloys:

* Alloy 601

* Alloy 602 CA and its variants MCA

* Alloy 617 and its variants 617 B and 617 OCC

* Alloy 625

* Alloy 690

* Alloy 699XA

* Alloy 718 and its variants

* Alloy 780

* Alloy 788

* Alloy 80A

* Alloy 81

* Alloy X-750

* Alloy C-263

* Alloy K-500

* Waspaloy

* FM 625

* FM 617 and

* FM 602

As an example, Tables 1 and 11 to 13 show the analytical ranges of the above-mentioned alloys.

An ingot form of more than 400 mm (round and polygonal) is achieved.

VIM, ESR and VAR ingots can also be forged with electrode dimensions to create better homogeneity, which may be required depending on the alloy and ingot diameter.

Hot forming for the required product shape and dimensions can be carried out by typical methods (forging, rolling, etc.).

Ingots and bars manufactured according to this method may be additionally manufactured in a semi-finished product shape (bar, sheet, strip, foil, wire, etc.) according to a conventional method.

By way of example, the method according to the invention is described as follows:

Several heats, for example S3 and S4, were prepared by the method according to the invention.

-The electrode was made by VIM.

-For reduction of stress and equilibrium of segregation, the electrodes were heat treated in a furnace for 10 to 72 hours in a temperature range of 500 to 1300 °C. In this process, heat treatment was applied for at least 10 hours and up to 48 hours in a temperature range of 1000°C to 1300°C.

-The electrode was cooled to a temperature in the air or in the furnace at room temperature to less than 900 °C.

-The electrode is subjected to a surface treatment such as grinding.

-The electrode was then remelted by ESR at a remelting rate of 3 to 6 kg/min to obtain an ESR ingot.

-The ESR ingot was cooled in the furnace to room temperature and below 900 °C.

-The ESR ingot was remelted by VAR at a remelting rate of 3-6 kg/min.

-The VAR ingot was thus heat-treated in the furnace for 20 to 100 hours in a temperature range of 500 to 1220 °C.

-The VAR ingot was then ground or not machined, either hot or cold worked with a bar.

In the comparison of Examples S1 and S2, without going through the method according to the invention, the electrodes produced by VIM are only in the temperature range of 500 to 1000° C. for 10 to 48 hours, for reduction of stress and equilibrium of segregation. Heat treatment only in the furnace.

All examples (both examples and comparative examples according to the invention) were prepared according to the analytical reports for alloy 718 (see Tables 1 and 11-13).

Deviations from the selected remelting rate that occurred during manufacturing are shown in Table 2.

The deviation of the remelting rate occurred to the following level.

S1 (414972) S2 (415078) S3 (415130) S4 (415156)
Upward deviation +26.39% +43.89% +2.2 +2.2 Downward deviation -40.83% -46.67% -0.83 -0.56

VDM alloy 601 VDM alloy 602 CA/MCA VDM FM 602 VDM alloy 617 (B/OCC) VDM FM 617 VDM alloy 625 Alloy 601 Alloy 602 CA/MCA FM 602 Alloy 617 (B/OCC) FM 617 Alloy 625 mass% Min-max Min-max Min-max Min-max Min-max Min-max C 0.03-0.1 0.15-0.25 0.15-0.25 0.05-0.08 0.05-0.15 -0.03 S -0.015 -0.01 -0.008 -0.01 N Cr 21-25 24-26 24-26 21-23 20-24 21-23 Ni 58-63 59-66 59-66 45-58 50-61 58-71 Mn -One -0.5 -0.5 -0.5 -One -0.5 Si -0.5 -0.5 -0.5 -0.3 -One -0.4 Mo 8-10 8-10 8-10 Ti -0.5 0.1-0.2 0.1-0.2 0.25-0.5 -0.6 -0.4 Nb -0.6 Cu -0.5 -0.1 -0.1 -0.5 Fe -18 8-11 8-11 -1.5 -3 -5 P -0.02 -0.02 -0.012 -0.03 -0.01 Al 1-1.7 1.8-2.4 1.8-2.4 0.8-1.3 0.8-1.5 -0.4 Mg Ca Rare earth V -0.6 Zr 0.01-0.1 0.01-0.1 W -0.5 Co -One 11-13 10-15 -One Y 0.05-0.12 La B -0.006 0.001-0.005 Hf Ta Ce O Pb Sn Zn Se Bi Sb CD Hg H As Nb+Ta 3.2-3.8 3.2-3.8

VDM FM 625 VDM alloy 690 VDM alloy 699XA VDM alloy 718 VDM alloy 718 CTP VDM FM 718 FM 625 Alloy 690 Alloy 699XA Alloy 718 Alloy 718 CTP FM 718 mass% Min-max Min-max Min-max Min-max Min-max Min-max C -0.1 -0.05 0.005-0.12 -0.08 -0.045 -0.08 S -0.015 -0.01 -0.015 -0.01 N -0.05 Cr 20-23 27-31 26-30 17-21 17-21 17-21 Ni 58-71 58-66 62-72 50-55 50-55 50-55 Mn -0.5 -0.5 -0.5 -0.35 -0.35 -0.3 Si -0.5 -0.5 -0.5 -0.35 -0.35 -0.3 Mo 8-10 2.8-3.3 2.8-3.3 2.8-3.3 Ti -0.4 -0.6 0.65-1.15 0.8-1.15 0.7-1.1 Nb 3-4.1 -0.5 4.75-5.5 Nb+Ta 4.8-5.5 Cu -0.5 -0.5 -0.5 -0.3 -0.23 -0.3 Fe -5 7-11 -2.5 6-25 12-24 -24 P -0.02 -0.015 -0.01 -0.015 Al -0.4 2-3 0.2-0.8 0.4-0.6 0.2-0.8 Mg Ca Rare earth V Zr -0.1 W Co -One -One Y La B -0.008 -0.006 -0.006 -0.006 Hf Ta -0.05 Ce O Pb -0.0005 -0.001 Sn Zn Se -0.0003 -0.0005 Bi -0.00003 -0.00005 Sb CD Hg H As Nb+Ta 3.2-3.8 4.87-5.2

VDM alloy 780 VDM alloy 788 Waspaloy VDM alloy C-263 VDM alloy 80A VDM alloy 81 Alloy 780 Alloy 788 Waspaloy Alloy C-263 Alloy 80A Alloy 81 N07001 2.4654 mass% Min-max Min-max Min-max Min-max Min-max Min-max C -0.1 0.04-0.1 0.02-0.1 0.04-0.08 0.04-0.1 -0.08 S -0.015 -0.01 -0.03 -0.007 -0.015 -0.02 N -0.03 Cr 16-20 18-21 18-21 19-21 18-21 28-32 Ni 26-62 51-69 49.6-62.5 50-55 65-79 59-66 Mn -0.5 -One -One -0.6 -One -0.7 Si -0.3 -0.5 -0.75 -0.4 -One -0.7 Mo 2-4 3.5-5 5.6-6.1 -0.5 Ti 0.1-1 1.8-2.7 2.75-3.25 1.9-2.4 1.8-2.7 1.5-2.1 Nb Cu -0.5 -0.2 -0.5 -0.2 -0.2 -0.25 Fe -10 8-15 -2 -0.7 -1.5 -1.5 P -0.03 -0.02 -0.03 -0.015 Al 1-3 1-1.8 1.2-1.6 0.3-0.6 1-1.8 -1.2 Mg -0.01 -One Ca -0.01 Rare earth V Zr -0.05 0.02-0.12 0.01-0.1 W Co 15-28 3-7 12-15 19-21 01 March Y La B -0.02 -0.008 0.003-0.01 -0.005 -0.006 Hf Ta Ce O -0.02 Pb -0.002 Sn Zn Se Bi Sb CD Hg H As Nb+Ta 4-6

VDM alloy K-500 Alloy X-750 Alloy K-500 Alloy X-750 N07750 2.4669 mass% Min-max Min-max C -0.18 -0.08 S -0.01 -0.01 N Cr 14-17 Ni 63-70 70-77.5 Mn -1.5 -One Si -0.5 -0.5 Mo Ti 0.35-0.85 2.25-2.75 Nb 0.7-1.2 Cu 27-33 -0.5 Fe 0.5-2 5-9 P -0.02 Al 2.3-3.15 0.4-1 Mg Ca Rare earth V Zr W Co -One Y La B Hf Ta Ce O Pb -0.006 Sn -0.006 Zn -0.02 Se Bi Sb CD Hg H As Nb+Ta 0.7-1.2

Glossary

VIM: Vacuum Induction Melting

VOD: Vacuum Oxygen Decarburization

VLF: Vacuum Ladle Furnace

ESR: Electroslag Remelting

VAR: Vacuum Arc Remelting

Claims (14)

As a method for producing a nickel-based alloy,
-Electrodes are created by VIM, VOD or VLF,
-For stress reduction and over-aging, the electrode is heat treated for 10 to 336 hours in a temperature range of 500 to 1300 °C in a furnace, and heat treatment is at least 10 hours maximum in a temperature range of 1000 to 1300 °C Applied for 48 hours,
-The electrode is cooled in the air or in the furnace to a temperature above room temperature and below 900 °C,
-Then, the cooled electrode is remelted by ESR at a remelting rate of 3.0 to 10 kg/min to obtain an ESR ingot,
-The ESR ingot is cooled to a temperature of room temperature or higher and less than 900°C in air or in the furnace,
The ESR ingot is remelted again by VAR at a remelting rate of 3.0 to 10 kg/min and in a range of remelting rate fluctuations of less than 15%, more preferably less than 10%, ideally less than 5%. And
-The re-melted VAR ingot is heat treated for 10 to 336 hours in a temperature range of 500 to 1250 °C,
-Then, the VAR ingot has a desired product shape and dimensions through hot and/or cold working,
Manufacturing method. The method according to claim 1, wherein the electrode undergoes a surface treatment before remelting by ESR. The method according to claim 1 or 2, wherein, before remelting by VAR, the ESR ingot undergoes surface treatment. As a method for producing a nickel-based alloy,
-The electrode is created by VIM,
-When the nickel-based alloy forms a gamma prime phase: the electrode is introduced into the furnace before it is colder than 200 °C, ideally before it is colder than 250 °C,
-For stress reduction and over-aging, the electrode is heat treated in the furnace for 10 to 336 hours in a temperature range of 500 to 1250 °C,
-The electrode is cooled in the air or in the furnace to a temperature above room temperature and below 900 °C,
-The surface of the electrode is machined (e.g., by brushing, grinding, pickling, cutting, scalping, etc.) for defect removal and cleaning. ,
-Then, the cooled electrode was remelted by ESR at a remelting rate of 3.0 to 10 kg/min to obtain an ESR ingot having a diameter of 400 to 1500 mm,
-The ESR ingot is cooled in the air or in the furnace to a temperature above room temperature and below 900°C,
-If necessary, the surface of the ESR ingot is machined for defect removal and cleaning (e.g., by brushing, grinding, pickling, cutting, scalping, etc.),
-The cooled ESR ingot is further heat-treated for 10 to 336 hours in a temperature range of 500 to 1250 °C,
-The ESR ingot is cooled in air or in the furnace to a temperature above room temperature and below 870 °C,
The ESR ingot is remelted again by VAR at a remelting rate of 3.0 to 10 kg/min and at a range of remelting rate of less than 15%, more preferably less than 10%, ideally less than 5%, VAR ingots with a diameter of 400 to 1500 mm are obtained,
-When the nickel-based alloy forms a gamma prime phase: the VAR ingot is introduced into the furnace before it is colder than 200 °C in the upper region, ideally before it is colder than 250 °C,
-The re-melted VAR ingot is heat treated for 10 to 336 hours in a temperature range of 500 to 1250 °C,
-The VAR ingot is cooled in the furnace or in the furnace to a temperature above room temperature to less than 900 °C, or transferred to a hot working process while hotter than 850 °C,
-The VAR ingot is then hot and/or cold worked (e.g., forged, rolled, drawn) to the desired product shape (e.g. ingot, bar, wire, sheet, strip, foil) and dimensions. Having,
Manufacturing method. The VAR ingot is remelted in an additional step of being remelted by VAR at a remelting rate of 3.0 to 10 kg/min, and then at 500 to 1300°C. A method of manufacturing, which is heat treated for 10 to 336 hours in a temperature range. The manufacturing method according to any one of claims 1 to 5, wherein, after the final heat treatment, the VAR ingot is cooled in air or in the furnace to a temperature of room temperature or higher and less than 900°C. The method according to claim 1, wherein after the final heat treatment, the VAR ingot is delivered to a hot working process at a temperature above 800° C., while still hot. The manufacturing method according to any one of claims 1 to 7, wherein an alloy of the following composition is used:
Up to 0.25 wt% C;
S up to 0.03 wt%;
Cr of 17 to 32 wt%;
33 to 72 wt% Ni;
Up to 1 wt% Mn;
Up to 1 wt% Si;
0 to 10 wt% Mo;
Ti up to 3.25 wt%;
Up to 5.5 wt% Nb;
Up to 0.5 wt% Cu;
Up to 25 wt% Fe;
Up to 0.03 wt% P;
Up to 3.15 wt% Al;
Up to 0.6 wt% V;
Zr up to 0.1 wt%;
Up to 35 wt% Co;
Up to 0.02 wt% B; And
Manufacturing-related impurities. The manufacturing method according to any one of claims 1 to 8, wherein an alloy of the following composition is used:
Up to 0.08 wt% C;
S up to 0.015 wt%;
Cr of 17 to 21 wt%;
50 to 55 wt% Ni;
Mn up to 0.35 wt%;
Up to 0.35 wt% Si;
2.8 to 3.3 wt% Mo;
0.65 to 1.15 wt% of Ti;
4.75 to 5.5 wt% of Nb;
Up to 0.3 wt% Cu;
6 to 25 wt% Fe;
Up to 0.015 wt% P;
0.2 to 0.8 wt% Al;
Up to 1 wt% Co;
Up to 0.006 wt% B;
Pb up to 0.001 wt%;
Se up to 0.0005 wt%;
Up to 0.00005 wt% Bi;
4.75 to 5.5 wt% of Nb+Ta; And
Manufacturing-related impurities. The manufacturing method according to any one of claims 1 to 8, wherein an alloy of the following composition is used:
Up to 0.1 wt% C;
S up to 0.015 wt%;
Up to 0.03 wt% N;
Cr of 16 to 20 wt%;
26 to 62 wt% Ni;
Up to 0.5 wt% Mn;
Up to 0.3 wt% Si;
2 to 4 wt% Mo;
0.1 to 1 wt% Ti;
Up to 0.5 wt% Cu;
Up to 10 wt% Fe;
Up to 0.03 wt% P;
1 to 3 wt% Al;
Up to 0.01 wt% Mg;
Up to 0.01 wt% Ca;
Zr up to 0.05 wt%;
15 to 28 wt% Co;
Up to 0.02 wt% B;
Up to 0.02 wt% O;
4 to 6 wt% Nb+Ta; And
Manufacturing-related impurities. The method according to claim 1, wherein the resulting VAR ingot has a diameter of more than 450 mm. 12. The method according to any one of claims 1 to 11, wherein the diameter of the resulting VAR ingot is greater than 500 mm. 13. The method according to any one of claims 1 to 12, wherein the resulting ingot does not contain remelting defects and has a comparative defect size of less than 0.8 mm in ultrasound examination. The method according to any one of claims 1 to 13, wherein the heat treatment of the VIM ingot is applied for a minimum of 10 hours and a maximum of 48 hours in a temperature range of 1000°C to 1300°C.